Easy-opening can end



y 7, 1968 O. L. BROWN 3,381,848

EASY-OPENING CAN END Filed Oct. 5, 1966 4 Sheets-Sheet 1 y 7, 1968 O. L. BROWN 3,381,848

EASY-OPENING CAN END Filed Oct. 5, 1966 4 Sheets-Sheet 2 I zzh w May 7, 1968 o. BROWN EASY-OPENING CAN END 4 Sheets-Sheet Filed Oct. 5 1966 lA/V'A/TOL Omar A. drawn ave ITI'O/LIVEV/ y 7; 1968 o. 1.. BROWN 3,381,848

EASY-OPENING CAN END Filed Oct. 5. 1966 4 Sheets-Sheet 4 m l [6i [9 [\l I I I Omar Z. drawn j -gm 3,381,848 EASY-OPENING CAN END Omar L. Brown, Dayton, Ohio, assignor, by mesne assignments, to Erma] C. Fraze, Dayton, Ohio Filed Oct. 5, 1966, Ser. No. 584,541 23 Claims. (Cl. 22054) This invention relates to a container having a portion of its wall weakened for severance and having a tab attached thereto to serve as a fingerpiece for initiating the severing operation. More particularly, the invention is directed to such a container in which the material of the container wall is deformed into engagement with the tab to anchor the tab without breaking the continuity of the container wall.

In one type of such a container, the wall of the container is weakened by scoring extending along a line that defines the removable portion of the container wall and the tab is connected to the removable portion by a hollow rivet that is formed in the container wall and extends through an aperture of the tab in engagement with the rim of the aperture. The engagement of the hollow rivet with the rim of the aperture of the tab is accomplished by squeezing the transverse end wall of the hollow rivet across its thickness to extrude the metal of the transverse end wall radially thereby forming a circumferential bead in overlapping engagement with the tab.

One of the features of the present invention is the attaching of the tab to the container wall be offsetting two spaced portions of the container wall to form two hollow anchoring bosses with beads in overlapping engagement with two opposite edges of the tab. In this manner, the tab is engaged at widely spaced points to cause the portion of the tab in the region of the two points to be tightly clamped against the removable container wall. In one preferred practice of the invention the opposite edges of the tab are notched or recessed to receive two hollow anchoring bosses or anchor members with the consequent advantage that the tab is completely immobilized with respect to relative motion in directions parallel with the container wall. In another embodiment, a similar result is achieved by utilizing two hollow anchoring bosses which extend through two spaced apertures in the tab.

The new method of attachment employs two cooperating hollow anchoring bosses instead of one hollow rivet and thus makes available a large total bead length for securely clamping the tab to the container wall. The new method of attachment further differs from former methods in that the bead is formed by deforming the anchoring boss laterally over the adjacent edges of the tab while restricting bead formation in a direction away from the tab. Thus, instead of forming a bead around the entire circumference of the anchoring boss, the bead is concentrated in a restricted circumferential region to form a strong hear of lesser circumferential extent.

One prior art type container includes an apertured tab anchored to a container wall by a single hollow rivet with an end portion of the tab engaging or substantially engaging a line of weakness formed in the container wall. Upon moving a handle portion of the tab away from the container wall, the end portion of the tab, which may be a sharp projection, engages the container wall and causes severance thereof along the line of weakness. In this type of container, it is important that the end portion or puncturing end of the tab engage the container wall at a preselected location which is on or closely adjacent the line of weakness. If the puncturing end of the tab does not engage the container wall at this preselected location, severance of the line of weakness by the tab will be diflicult or impossible.

One difficulty with prior art containers of this type is that the single rivet and apertured tab construction fre- States Patent ice quently allows relative lateral pivotal movement between the tab and the container wall thereby moving the puncturing end of the tab away from the preselected location to a location where severance along the line of weakness becomes diliicult or impossible. Such lateral pivotal movement may be brought about by the forces that may be applied to the tab during handling of the container. The user is therefore required to rotate the tab in an attempt to accurately position the puncturing end at the preselected location. As the clamping force of the bead of the single rivet may offer some friction resistance to such relative pivotal movement, and as it is somewhat difficult to visually ascertain when the puncturing end of the tab is at the preselected location, it is quite difficult for the user to accurately position the puncturing end of the tab.

The present invention eliminates the above noted problem in providing two anchoring bosses integral with the container wall which positively retain the tab against the container wall and positively prevent any substantial relative lateral pivotal movement between the tab and the container wall. This assures that the puncturing end of the tab will remain at the preselected location even though the tab is subjected to relatively large forces tending to cause lateral pivotal movement thereof. The two anchor members of this invention accomplish this desirable result either by overlapping opposed peripheral edges of the tab or by extending through separate apertures in the tab.

Containers in which the line of weakness forms a tear strip which covers a major portion of one wall of the container are known as full panel pullouts. Rupture of the line of weakness in full panel pullouts is often initiated by a tab of the type described above in which a bearing portion or force applying end of the tab engages or substantially engages the line of weakness and causes rupture thereof as by puncturing. To facilitate manipulation of the tab in initiating severance of the tear strip, it is desirable that the rivit used to secure the tab to the tear strip be positioned as closely as possible to the bearing portion of the tab so that a relatively long lever portion will be available as a handle portion to provide a large mechanical advantage. In the case of full panel pullouts, the score line or line of weakness is usually positioned very close to the head on the can end that is used to secure the can end to the side wall of the container. One factor that has prevented positioning the rivet close to the score line is that the integral rivet cannot be formed close to the securing bead. This is because the rivet is formed in several stages, the first of which is the formation of a relatively large dimple in the container wall. The dimple is then reformed into a hollow rivet of lesser area in plan than the dimple. In the case of a full panel pullout, the relatively large dimple can be formed as close to the edge or bead of the can end as possible, but when the dimple is reformed into a hollow riviet, the resulting hollow rivet is spaced inwardly a substantial distance from the edge of the can end. This leaves a shorter lever for initiating severance of the score line and increases the force required to cause such severance. Although the overall tab length could be increased to partially alleviate this problem, this results in the need for additional metal for the tab and causes the tab to appear somewhat unsightly.

According to the present invention, the initial severance of a tear strip such as a full panel pullout is facilitated by the provision of a hinge in the container wall. Such hinge may include a score line and is preferably positioned intermediate the line of weakness defining the tear strip and the anchoring bosses used to secure the tab to the container wall. Thus, when the handle end of the tab is moved away from the container wall and the bearing portion or force applying end of the tab applies a force to or adjacent the score line defining the tear strip, the container wall can bend relatively easily about the hinge. As the hinge offers little resistance to the bending forces applied by the tab, the primary resistance to lifting of the tab is due to the resistance of the score line defining the tear strip.

To further facilitate severance of the score line, the anchoring bosses used to secure the tab to the container wall are formed much closer to the score line than has been possible heretofore. The result is that the anchoring bosses divide the tab into a relatively long lever portion or handle portion and a relatively short lever portion. Thus a relatively large mechanical advantage is provided which substantially facilitates severance of the tear strip.

The process for producing the anchoring bosses very close to the score line is characterized by forming a dimple in the sheet material with which the dimple having a wall with a thickened portion in the central region thereof. The thickness of the wall of the dimple progressively decreases as it extends toward the thickened portion. The area of the dimple in plan is much less than the area of the dimple required in the formation of the usual rivet.

The dimple is next reformed into a hollow anchoring boss which may be, if desired, of substantially the same height above the container wall as the dimple. In one preferred form, two spaced anchoring bosses are formed, each of which has a sloping wall and a relatively straight wall and the tab is positioned between the straight walls of the two anchoring bosses. Finally, the anchoring bosses are staked to form a bead that overlaps and clamping retains the tab to the container wall. Alternatively, a pair of hollow rivets may be formed and extended through apertures in the tab. In either embodiment, however, the anchoring members are formed close to the score line.

The invention, both as to its organization and method of operation, together with further features and advantages thereof may best he understood by reference to the following description taken in connection with the accompanying illustrative drawings in which:

FIG. 1 is a top plan view of a can end embodying one form of the present invention;

FIG. 2 is an enlarged fragmentary plan view showing two anchoring bosses clamping the tab to the tear strip;

FIG. 3 is an enlarged fragmentary sectional view taken along line 3-3 of FIG. 2 and illustrating the force applying end of the tab and the two lines of weakness formed in the can end;

FIG. 4 is a fragmentary sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a fragmentary sectional view taken along line 5--5 of FIG. 2 and iliustrating how the anchoring bosses clamp the tab to the can end;

FIG. 6 is a longitudinal sectional view illustrating a pair of dies after they have been utilized to form a dimple in the can end, the formation of the dimple being the first step in the formation of one of the anchoring bosses;

FIG. 7 is a longitudinal sectional View through a second pair of dies after they have been utilized to re form the dimple illustrated in FIG. 6;

FIG. 8 is a longitudinal sectional view illustrating a third pair of dies just prior to forming the anchoring boss into clamping engagement with the tab;

FIG. 9 is a view similar to FIG. 8 after the dies have deformed the anchoring boss into clamping engagement with the tab;

FIG. 10 is a top plan view similar to FIG. 1 illustrating a second embodiment of the invention; and

FIG. 11 is an enlarged fragmentary sectional view taken along line Iii-13 of FIG. 10.

Referring to the drawings and in particular to FIGS.

1-5 thereof, reference numeral 115 designates a container wall such as a can end having a peripheral head 17 for attaching the can end to a side wall of a container (not shown). A circular line of weakness or score line 19 is formed in the can end to define a tear strip or removable panel 21. The residual web thickness of the can end 15 along the score line 19 is sized to allow easy rupture of the can end therealong. In the embodiment shown in FIGS. l-S, the score line 19 is closely adjacent the peripheral head 17, and accordingly, the removable panel 21 covers a major portion of the can end 15. This type of can end is known as a full panel pullout.

A tab 23 is secured to the removable panel 21 by a pair of anchoring bosses 25 and 27. A hinge 29, such as a score line, is formed in the can end 15 intermediate the bosses 25 and 2'7 and the score line 19. The residual web thickness along the score line 29 is greater than along the score line 19 so as to permit relatively easy bending of the can end along hinge 29 while preventing rupture thereof during manipulation of the tab 23.

More particularly, the can end 15 is preferably formed from aluminum sheet stock of up to approximately .015 inch thickness. The material of the can end 15 is deformed to form an inwardly extending circular stiffening bead 31 which also utilizes some of the excess metal produced in the formation of scoring lines 19 and 29'. The can end 15 has a central depression 33 which also stiffens the can end and provides a slight clearance space between the underside of the tab 23 and the can end to facilitate lifting of the tab.

The tab 23 which is also formed from metal sheet material has a ring or handle portion 35 and a relatively broad portion 37 which terminates in a force applying end or toe 39. The tab 23 is made longitudinally rigid by three longitudinally extending stiffening ribs 41, 43 and 45 formed integrally in the broad portion 37.

The tab 23 has a pair of opposed lateral parallel peripheral edges 47 and 49 in which a pair of identical notches 51 and 53, respectively, are formed. The tab 23 is formed with a peripheral bead 55 which terminates in head ends 55:; and 55b (FIG. 4) which lie closely adjacent the ends of the notches as illustrated in FIG. 4. The material of the tab 23 slopes downwardly from the tops of the bead ends 55a and 55b to form a ramp 57. As best seen in FIG. 2, the ramp 57 extends completely around the notch 51 and is spaced from the innermost edge of the notch 51 by a generally planar foot 59 which engages the can end 15 (FIGS. 2 and 5). Thus, the rim of the notch 51 lies in close proximity to the can end 15. The characteristics of the tab 23 adjacent the notch 53 are similar and are identified by corresponding primed reference characters.

The anchoring bosses 25 and 27 are formed integrally in the can end 15 by a process that is described hereinafter. The anchoring bosses 25 and 27 are formed with beads 61 and 63, respectively, that overhang the peripheral edges of the tab and clampingly engage the feet 59 and 59', respectively. The feet 59 and 59' are thus tightly retained against the can end 15. Similarly, the anchoring bosses 25 and 27 extend longitudinally of the tab 23 toward the bead ends 55a and 55b so as to overhang and clampingly engage portions of the ramps 57 and 57', respectively (FIG. 4). The tab 23 is thus tightly secured against the container Wall 15 and prevented from pivoting laterally relative to the container wall. In forming the anchoring bosses 25 and 27, an area. of the can end 15 immediately surrounding the anchoring .bosses may be coined, if desired.

With the tab thus secured to the can end 15, the toe 39 bears on the can end 15 closely adjacent the scoreline 19 (FIGS. 1 and 3). The toe 39 preferably bears against the container end 15 at the inner edge of the scorelinc 19. As shown in FIG. 3, the underside of the peripheral head 55 at the toe 39 bears on the can end '15. To concentrate the force applied to the can end by the toe 39, the tab 23 is tapered so that the area of engagement between the toe and can end is relatively small.

The tab 23 is thus secured to the can end 15 by the bosses 25 and 27 and extends across the hinge 29. The bosses 25 and 27 divide the tab 23 into a relatively long lever portion which extends toward the center of the can end and a relatively short lever portion which extends toward the scoreline 19 and terminates in the toe 39. In using the invention, the ring of the tab is lifted, there by forcing the toe 39 ti htly against the can end 15 closely adjacent the scoreline 19. Each incremental movement of the ring 35 away from the can end 15 causes the toe to apply additional force to the can end 15 with a relatively high mechanical advantage. Such movement of the tab 23 is faciiitated by the hinge 29 which permits relatively easy bending of the can end 15 therearound. When the ring 35 has been moved a sufficient distance away from the can end 15, the scoreline 19 will rupture to thereby allow the panel 21 to be completely manually removed from the can end '15.

The two bosses 25 and 27 positively prevent relative lateral pivotal movement between the tab 23 and the can end 15, thereby preventing movement of the toe 39 away from the scoreline 19. Thus, regardless of any rough handling to which the tab 23 may be subjected, the toe 39 remains in the preferred preselected position closely adjacent the scoreline 19. The notches 51 and 53 cooperate with the bosses 25 and 27 to prevent relative longitudinal or transverse shifting movement of the tab 23 relative to the can end 15. The hinge 29 is useful in reducing the resistance of the can end to bending during manipulation of the tab.

FIGS. 6-9 illustrate a preferred method of forming the anchoring bosses 25 and 27. In this preferred method, a dimple is formed (FIG. 6), the dimple is then reformed as shown in FIG. 7 into a hollow anchoring boss which is staked as shown in FIGS. 8 and 9 into clamping engagement with the tab 23.

As shown in 'FIG. 6, the can end 15 is offset by a lower female die 69 and an upper male die 71 to form a dimple 73. The male die has a working face 75 which cooperates with a die cavity 77 and an axial passageway 79 in the female die 69 to form the dimple 73. The working face 75 and the die cavity 77 may both be generally hemispherical with the radius of the working face being less than the radius of the die cavity so that the working face and die cavity will be spaced a greater amount adjacent the plane of the can end 15 than within the dimple.

The dimple 73 thus formed has a sloping sidewall 81 of progressively decreasing thickness as it extends from a base 83 of the dimple to a central region 85 of the dimple. The central region '85 is substantially thicker than the surrounding portions of the sloping wall 81 and this effect can be accentuated by slightly flattening the portions of the working face 75 that are aligned with the passageway 79. By way of illustration, when sheet stock of .015 inch thickness is used for the can end 15, the dimple 73 may have a wall thickness of approximately .014 inch adjacent the base 83, a thickness of approximately .009 inch immediately adjacent the central region 55, and the central region may have a thickness of .0135 inch or approximate the original thickness of the sheet stock. The diameter of the dimple 73 across the base 83 and the height thereof may be varied as required. The progressive thinning of the wall 81 of the dimple causes the can end 15 to raise slightly, e.g., .015 inch above the female die 69. Because of this raising of the can end 15, it is preferred to form the dimple in the inverted position shown in FIG. 6.

FIG. 7 illustrates how the dimple 73 is formed into a hollow anchoring boss 87 by a male die 89 and a female die 91. The die 89 has a working face 93 with an arcuate surface and a straight surface and the die 91 has a die cavity 95 with substantially correspondingly shaped :arcuate and straight surfaces. The arcuate face of the die cavity 95 may be formed with a passageway 97 to accommodate at least a portion of the thickened central region 35 of the dimple 73. The resulting boss 87 has a sloping arcuate wall 99 with a thickened central portion 101 and a straight wall 193 which is generally perpendicular to the plane of the can end 15. In the embodiment illus- I trated, the height of the boss is equal to the dimple height. The portion 101 of the boss 87 has a slightly smaller diameter than the portion 35 of the dimple 73 as a corner of the portion 85 is engaged by the dies and used to form a portion of the wall 103.

Next, the foot 59 of the tab 23 is placed in engagement with the wall 193 of the boss 87 (FIG. 8) with the sides of the notches partially surrounding the arcuate wall 99. In actual practice, two of the anchoring bosses 87 will be formed in the can end 15 and spaced so that the walls 103 of each are confronting to allow the feet 59 and 59' of the tab 23 to be placed in engagement therewith.

Next, an anvil 199 of a die member 111 is inserted into the hollow boss 87. The anvil has a working face 113 which is inclined upwardly from the can end 15 as it extends toward the tab 23. A hammer or punch 115 having a surface 117 that also extends upwardly as it extends toward the tab 23 is provided for cooperating with the anvil 109. As shown in FIG. 8, the anvil 109 preferably extends axially into the hollow boss 87 and terminates short of the central portion 101.

Finally, the punch 115 is advanced toward the boss 87 and deforms the latter as shown in FIG. 9. The inclined surfaces 113 and 117 cooperate to slightly fold the boss 87 laterally over the foot 59 of the tab 23. The surfaces 113 and 117 extrude the wall of the boss 87 and the central region 101 sufiiciently to force some of the metal thereof radially outwardly to assist in formation of the head 61. Such extrusion also assists the formation of the portion of the head that extends longitudinally of the tab and overlaps the ramp 57 (FIG. 4). The inclined surfaces 113 and 117 also restrict or prevent bead formation in a direction away from the tab 23.

The process described above for producing the bosses 25 and 27 is preferred because the bosses are very strong and because the diameter of the dimple 73 is less than the diameter of the dimples formed heretofore in connection with the production or rivets for securing tabs to tear strips. Thus, the anchoring bosses 25 and 27 may be positioned closed to the head 17 than has been possible heretofore. This is important in a full panel pullout to allow the maximum mechanical advantage during manipulation of the tab. This method of boss formation is also preferred because the unstaked hollow boss 87 has the thickened central region 101. Thus, a relatively large amount of metal is available in the walls of the rivet for forming the bead 61. This results in the formation of a very strong bead which securely clamps the tab 23 against the can end 15. Finally, the process described above permits staking of the boss 87 generally laterally thereof to form a bead substantially all of which overlies a portion of the lab 23. Thus, substantially all of the head 61 to utilized to secure the tab 23 to the can end 15.

FIGS. 10 and 11 illustrate a second embodiment of the invention in which two anchoring bosses or rivets 119 and 121 are utilized to secure a tab 23 to a can end 15'. Except as specifically noted herein, the embodiment of FIGS. 10 and 11 is identical to the embodiment of FIGS. 1-5 and corresponding primed reference characters are utilized in the embodiment of FIGS. 10 and 11 to identify corresponding parts.

The tab 23 is provided with reinforcing ribs 123 to make the tab longitudinally rigid. The tab 23' has a pair of spaced apertures 125 and 127 therein and has a narrow force applying end or toe 39 which lies closely adjacent the scoreline 19' as best shown in FIG. 13. A peripheral bead 55 maintains a major portion of the tab 23 spaced from the can end 15 and an annular portion 129 surrounding each of the apertures 125 and 127 to offset downwardly into engagement with the can end 15'.

The rivets 119 and 121 are formed integrally with the can end 15 and extend through the apertures 125 and 127, respectively, of the tab 23. The tab 23' is thus firmly anchored to the can end 15' and is incapable of pivoting laterally relative to the can end. As described in connection with the previous embodiment, the toe 3% is rigidly held closely adjacent the scoreline 19'. Thus, the embodiment of FIGS. 10 and 11 possesses many of the advantages discussd above in connection with the above-described embodiment.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications, and substitutions may be made by those having ordinary skills in the art without necessarily departing from the spirit and scope of this invention.

What is claimed is:

1. In a container, the combination of:

a container wall of sheet material;

a first line of weakness in said container wall defining a tear strip manually removable therefrom;

a second line of weakness in said container wall adjacent said first line of weakness and defining a hinge, said hinge being spaced from said first line of weakness by a portion of said tear strip;

a tab lying at least partially within the area of said tear strip, said tab having a handle end and a force applying end with the force applying end lying at a preselected location closely adjacent said first line of weakness; and

means integral with said tear strip for securing said tab to said tear strip, movement of said handle end of said tab urging said force applying end firmly against said container wall to cause hinged movement of said portion of said container wall about said hinge to initiate severance of the tear strip along said first line of weakness.

2. A combination as defined in claim 1 wherein said hinge lies within said tear strip and said tab extends across said hinge.

3. A combination as defined in claim 2 wherein said tear strip extends over a major portion of said container wall.

4. .A combination as defined in claim 2 wherein said hingle lies intermediate said last mentioned means and said first line of weakness and said preselected location is on said tear strip.

5. .A combination as defined in claim It wherein said last mentioned means includes a pair of anchor members engageable with spaced portions of said tab to rigidly secure said tab to said container wall and to substantially prevent relative lateral pivotal movement between said tab and said container wall thereby assuring that said force applying end will remain at said preselected location.

6. In a container, the combination of:

a container wall of sheet material;

a line of weakness in said container wall, said line of weakness being rupturable to define an opening in said container wall;

a tab of sheet material for initiating rupture of said line of weakness, said tab having a handle end and a force applying end, said force applying end lying at a preselected location closely adjacent said line of weakness; and

teams integral with said container wall for securing said tab to said container wall and for positively preventing any substantial relative lateral pivotal movement between said tab and said container wall to thereby accurately maintain said force applying end at said preselected location whereby manipulation of said handle end causes said force applying end to bear against said container wall at said preselected location to rupture said line of weakness.

7. A combination as defined in claim 6 wherein said tab has a pair of spaced apertures therein adjacent said force applying end and said last mentioned means includes a pair of anchor members integral with said container wall and extending through said apertures to secure said tab to said container wall.

8. A combination as defined in claim 6 wherein said tab has first and second generally opposed. peripheral edges adjacent said force applying end and said last men tioned means includes first and second anchor members positioned respectively adjacent said first and second peripheral edges, each of said rivets having a bead portion overhanging the adjacent peripheral edge of said tab to firmly clamp the tab against said container wall.

9. A combination as defined in claim 6 wherein said line of weakness defines a tear strip manually removable from said container wall, said last mentioned means is formed integrally with said tear strip to firmly secure said tab to said tear strip, said tab being tapered in plan and terminating in said force applying end to concentrate the force applied to said container wall during said manipulation of said handle end.

it In a container, the combination of:

a container wall of sheet material;

a line of weakness in said container wall, said line of weakness being rupturable to define an opening in said container wall;

a tab for initiating rupture of said line of weakness, said tab having first and second lateral edges and a handle portion; and

first and second anchoring bosses formed integrally with said container wall, portions of said first and second anchoring bosses overhanging said lateral edges of said tab and firmly clamping said tab against said container wall whereby manipulation of said handle portion initiates rupture of said line of weakness.

11. A combination as defined in claim 10 wherein said anchoring bosses serve as a fulcrum connection to divide said tab into a relatively long lever portion that includes the handle portion and a relatively short lever portion, said relatively short lever portion terminating in a force applying end, said force applying end lying closely adjacent said line of weakness and bearing against said container wall. upon said manipulation of said handle portion to forcibly initiate rupture of said line of weakness.

12. In a container, the combination of:

a container wall of sheet material;

a line of weakness in said container wall, said line of weakness being rupturable to define an opening in said container Wall;

a tab for initiating rupture of said line of weakness, said tab having first and second opposed edges with first and second notches formed respectively therein; and

first and second anchoring bosses formed integrally with said container wall without breaking the continuity of said container wall, said first and second anchoring bosses extending through said first and second notches, respectively and interlocking therewith to prevent substantial relative movement between said tab and said container wall, each of said anchoring bosses having a bead overlapping at least a portion of the rim of its associated notch to clamp said tab against the container wall.

13. A combination as defined in claim 12 wherein said tab has a peripheral bead extending along the container wall, said peripheral bead being discontinuous at said notches.

14. A combination as defined in claim 13, wherein said peripheral bead spaces a portion of said tab from said 9 container wall, said tab being offset toward said container wall at said notches so that the rims of said notc es lie closely adjacent to the container wall.

15. A method of attaching a tab to a container Wall to serve a means for initiating severance of a portion of the container wall, characterized by the steps of:

placing the tab facewise against the container wall,

the tab having first and second generally opposed edges;

forming first and second hollow anchoring bosses in the container wall adjacent said first and second edges of the tab, respectively; and

deforming the first and second hollow anchoring bosses to form beads overlapping the first and second op posed edges of the tab, respectively, and clamping the tab against the container wall. 16. A method as defined in claim 15 including the step of forming first and second notches in said first and second edges of the tab, respectively, said first and econd notches receiving and interlocking with said first and second hollow anchoring members.

17. A method as defined in claim 15, including restricting the formation of said bead in a direction away from said tab to cause a major portion of said head to overhang said tab.

13. In a method of attaching a tab to a container wall to serve as means for initiating severance of a portion of the container wall, the steps of:

placing the tab tacewise against the container Wall,

said tab having generally opposed edges; and

deforming portions of the container wall adjacent said opposed edges of the tab into clamping engagement with the opposed edges of the tab without breaking the continuity of the material of the container wall.

19. A method as defined in claim 18 including forming a line of weakness in the container wall, said line of Weakness being rupturable by movement of said tab away from the container wall.

20. A method as defined in claim 19 including forming notches in said opposed edges of said tab, said step of deforming including forcing said portions of the container wall into clamping engagement with the rims of said notches.

21. In a method of attaching a tab to a container wall to serve as means for initiating severance of a portion of the container wall without removing the tab from the container wall, the steps of:

providing a section of sheet material;

forming a dimple in said sheet material with the dimple having a Wall with a thickened portion in the central region thereof;

reforming said dimple into a hollow anchor member having a sloping wall with an outer surface and a relatively straight wall;

positioning a tab having a peripheral edge on said sheet material with said peripheral edge lying closely adjacent said relatively straight wall; and

staking said anchor member to form a bead that overlaps and clampingly retains said tab to said section of sheet material.

22. A method as defined in claim 21 wherein the thickness of said wall of said dimple progressively decreases from the section of sheet material to said thickened portion.

23. A method as defined in claim 21 wherein said step of staking includes inserting a male die having a die face inclined upwardly from said section of sheet material as it extends toward said tab into said hollow anchor member and striking the outer surface of said anchor member with a punch having a punch face inclined upwardly as it eXtends toward said tab.

References Cited UNITED STATES PATENTS 2,029,329 2/1936 Ljungstl'om et a] 2Z()54 3,215,305 11/1965 Frankenberg 22054 3,301,432 1/1967 Novak 22054 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner. 

1. IN A CONTAINER, THE COMBINATION OF: A CONTAINER WALL OF SHEET MATERIAL; A FIRST LINE OF WEAKNESS IN SAID CONTAINER WALL DEFINING A TEAR STRIP MANUALLY REMOVABLE THEREFROM; A SECOND LINE OF WEAKNESS IN SAID CONTAINER WALL ADJACENT SAID FIRST LINE OF WEAKNESS AND DEFINING A HINGE, SAID HINGE BEING SPACED FROM SAID FIRST LINE OF WEAKNESS BY A PORTION OF SAID TEAR STRIP; A TAB LYING AT LEAST PARTIALLY WITHIN THE AREA OF SAID TEAR STRIP, SAID TAB HAVING A HANDLE END AND A FORCE APPLYING END WITH THE FORCE APPLYING END LYING AT A PRESELECTED LOCATION CLOSELY ADJACENT SAID FIRST LINE OF WEAKNESS; AND MEANS INTEGRAL WITH SAID TEAR STRIP FOR SECURING SAID TAB TO SAID TEAR STRIP, MOVEMENT OF SAID HANDLE END OF SAID TAB URGING SAID FORCE APPLYING END FIRMLY AGAINST SAID CONTAINER WALL TO CAUSE HINGED MOVEMENT OF SAID PORTION OF SAID CONTAINER WALL ABOUT SAID HINGE TO INITIATE SEVERANCE OF THE TEAR STRIP ALONG SAID FIRST LINE OF WEAKNESS. 